Calcareous dinoflagellate cysts and the Turonian nutrient crisis - Data from the upper Turonian of the Lower Saxony Basin (northern Germany)

Little information exists on the distribution of calcareous dinoflagellate cysts from the Turonian (Upper Cretaceous) of Germany, and the first taxonomic assessment of late Turonian calcareous dinoflagellate cysts from the Salder Formation (NW Germany, Lower Saxony Basin) is a first step to close this gap. Ca. 11.000 calcareous dinoflagellate cysts were considered for this study, representing seven taxa only. The dominant taxon is Pithonella, mainly represented by Pithonella sphaerica and Pithonella ovalis, while Pithonella cardiiformis and Pithonella discoidea are rare. The species Pithonella spiralis n. sp. is newly described. Non-pithonellid c-dinocysts are represented by Normandia circumperforata and Pirumella sp. The late Turonian c-dinocyst diversity of the NW German shelf sea is extremely low compared with the Early Cretaceous species richness in the same area. The diversity drop is explained to result from a Turonian nutrient crisis, caused by the drowning of source areas of nutrient input during the early Late Cretaceous sea-level highstand.